The data type of void is a special kind of data or object that actually does not have any type to begin with. No data type is returned. That is, the return of this data type will have no value. Examples of such data type include certain functions that print a message but do not have any return value.
You need to understand this part in order to understand the language better which allows you to manipulate the functions and the commands effectively. Understanding the important details is key to learning the language faster.